JP2018059697A - Reduced-pressure drying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reduced-pressure drying apparatus that has a simple configuration and conducts both reduced-pressure drying of a solvent on a substrate and separation of the solvent from a solvent collecting unit, for shortening the time to conduct both the reduced-pressure drying and the separation of a solvent.SOLUTION: A reduced-pressure drying apparatus 1, for drying a solution on a substrate W stored in a chamber 10 in a depressurized state, includes a solvent collecting unit 30 that is a net-shaped plate and is configured to temporarily collect a solvent in the solution vaporized from the substrate W. The solvent collecting unit 30 is provided to face the substrate W in the chamber 10, and the net-shaped plate constituting the solvent collecting unit 30 has an opening ratio of 60% or more and 80% or less and a thermal capacity per unit area of 850 J/K mor less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vacuum drying apparatus for drying a solution on a substrate housed in a chamber in a vacuum state.

  2. Description of the Related Art Conventionally, an organic light emitting diode (OLED) that is a light emitting diode using light emission of organic EL (Electroluminescence) is known. An organic EL display using such an organic light emitting diode is advantageous in that it is thin and lightweight, has low power consumption, and is excellent in response speed, viewing angle, and contrast ratio. In recent years, it has attracted attention as a panel display (FPD).

  The organic light emitting diode has a structure in which an organic EL layer is sandwiched between an anode and a cathode on a substrate. The organic EL layer is formed, for example, by laminating a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer in this order from the anode side. In forming each layer of these organic EL layers (in particular, a hole injection layer, a hole transport layer, and a light emitting layer), for example, a method of discharging droplets of an organic material onto a substrate by an inkjet method is used.

  A large amount of solvent is contained in the organic material discharged onto the substrate by the inkjet method. Therefore, for the purpose of removing the solvent, a reduced-pressure drying process for drying the solution on the substrate in a reduced pressure state is performed (see Patent Documents 1 to 3).

Specifically, the drying apparatus disclosed in Patent Document 1 is provided with a processing container that can be evacuated, a mounting table that supports a substrate in the processing container, and a substrate that is supported by the mounting table. And a solvent collecting unit that collects a solvent that volatilizes from the organic material film.
The solvent collection part of the drying apparatus of this patent document 1 has a metal collection plate arrange | positioned substantially parallel to the surface of a board | substrate, The through-opening is formed in this collection plate. Moreover, the drying apparatus of patent document 1 is equipped with the solvent desorption apparatus for vaporizing again the solvent collected with the collection plate after the drying process is complete | finished, and desorbing from a collection plate. Furthermore, the drying device of Patent Document 1 has a temperature adjusting device composed of a Peltier element or the like in order to adjust the temperature of the collection plate.

  The drying apparatus of Patent Document 2 is arranged such that a porous adsorption member that adsorbs a solvent in a solution that evaporates at the time of drying faces a substrate. Moreover, in patent document 2, the drying apparatus which dries an adsorption | suction member is provided separately from the drying apparatus which adsorb | sucks and dries the solvent in the solution on a board | substrate. In this other drying apparatus, a temperature control unit is provided for temperature control on the mounting table on which the adsorption member is mounted.

JP 2014-199806 A JP 2010-169308 A Japanese Patent No. 5701782

  By the way, in order to shorten the processing time in the drying apparatus, including the time for desorption treatment of the solvent collected / adsorbed in the solvent collection part, the solvent collection efficiency in the solvent collection part is increased. It is necessary to improve or improve the vaporization efficiency of the solvent from the solvent collection part.

However, in the drying apparatus of Patent Document 1, the temperature at which the collection plate is cooled or heated in order to improve the solvent collection efficiency of the solvent collection unit, that is, the collection plate, and the evaporation efficiency of the solvent from the collection plate. An adjustment device is used, and the configuration of the device is complicated.
Also in the technique disclosed in Patent Document 2, since the temperature control unit is used for the mounting table on which the substrate is mounted in order to promote the evaporation of the solvent from the solvent collecting unit, that is, the adsorption member, the configuration of the apparatus Is complicated. Furthermore, in the technique disclosed in Patent Document 2, a drying device is used separately from the substrate drying device in order to dry the adsorption member.
Patent Document 3 does not disclose or suggest anything in this regard.

  The present invention has been made in view of this point, and performs both the reduced-pressure drying treatment of the solvent on the substrate and the desorption treatment of the solvent from the solvent collecting portion, and the time of the reduced-pressure drying treatment is as follows. It is an object of the present invention to provide a reduced pressure drying apparatus having a short desorption treatment time and a simple apparatus configuration.

  In order to achieve the above object, the present invention provides a vacuum drying apparatus for drying a solution on a substrate housed in a chamber in a reduced pressure state. A solvent collecting unit that temporarily collects the solvent; and the solvent collecting unit is provided to face the substrate in the chamber, and the pressure in the chamber is set at the temperature of the substrate. When the pressure in the chamber is reduced to below the vapor pressure, the gas in the chamber adiabatically expanded as the pressure is reduced, so that the temperature of the solvent collection unit is cooled below the dew point of the solvent at the pressure of the chamber at that time. Until the evaporation of the solvent of the solution on the substrate is completed, the temperature of the solvent collection unit is maintained below the dew point of the solvent at the pressure in the chamber at each time point. Within 5 minutes after the evaporation of the solvent is completed, the temperature of the solvent collecting part becomes equal to or higher than the dew point of the solvent at the pressure of the chamber at that time due to the radiant heat from the chamber. Yes.

Another aspect of the present invention is a reduced-pressure drying apparatus that dries a solution on a substrate housed in a chamber in a reduced pressure state, and includes a net-like plate, and temporarily removes the solvent in the solution evaporated from the substrate. A solvent collecting portion that collects in the chamber, the solvent collecting portion is provided so as to face the substrate in the chamber, and the mesh plate has an aperture ratio of 60% to 80%. The heat capacity per ² is 850 J / K or less.

  According to yet another aspect, the present invention provides a vacuum drying apparatus for drying a solution on a substrate housed in a chamber in a reduced pressure state. The vacuum drying device includes a mesh plate, and temporarily removes a solvent in the solution vaporized from the substrate. A solvent collecting portion for collecting the solvent, and the solvent collecting portion is provided so as to face the substrate in the chamber, and a distance from the substrate to the solvent collecting portion is the distance from the substrate to the solvent collecting portion. It is characterized by being 40% or more and 60% or less of the distance to the upper structure of the solvent collecting part.

  According to the present invention, it is possible to perform the solvent drying process on the substrate and the solvent desorption process from the solvent collecting unit in a short time with a simple apparatus configuration. Further, according to the present invention, the drying time of the solvent on the substrate can be made uniform in the same substrate.

It is a figure which shows schematic structure of the reduced pressure drying apparatus which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the attachment structure of a solvent collection part. It is explanatory drawing of the reduced pressure drying process using the reduced pressure drying apparatus of FIG. 4 is a diagram illustrating a vapor pressure curve of a solvent of a solution applied to a substrate W. FIG. It is a figure which shows the mode in the chamber of a reduced pressure drying apparatus. It is sectional drawing explaining the suitable processing method of the net-like board which comprises a solvent collection net | network. It is a longitudinal cross-sectional view which shows schematic structure of the reduced pressure drying apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows schematic structure of the reduced pressure drying apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows schematic structure of the reduced pressure drying apparatus which concerns on the 4th Embodiment of this invention. It is a figure which shows schematic structure of the reduced pressure drying apparatus which concerns on the 5th Embodiment of invention. It is a longitudinal cross-sectional view which shows schematic structure of the reduced pressure drying apparatus which concerns on 1st reference embodiment. It is a figure explaining the example of the collection part for withering which has a cooling heating mechanism. It is a longitudinal cross-sectional view which shows schematic structure of the reduced pressure drying apparatus which concerns on 2nd reference embodiment. It is a longitudinal cross-sectional view which shows schematic structure of the reduced pressure drying apparatus which concerns on 3rd reference embodiment. It is a figure which shows the time change of the temperature near the center of the solvent collection net | network in Example 1, and the pressure in a chamber. It is a figure which shows the time change of the temperature near the center of the solvent collection net | network in Example 1, and the pressure in a chamber. It is a figure which shows the time change of the temperature near the center of the solvent collection net | network in Example 1, and the pressure in a chamber. It is a figure which shows the time change of the temperature in each part of the solvent collection net | network in Example 1, and the time change of the pressure in a chamber.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol. Further, the present invention is not limited to the embodiments described below.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a vacuum drying apparatus according to the first embodiment of the present invention. FIG. 1A is a cross-sectional view schematically showing the configuration of the vacuum drying apparatus, and FIG. It is a top view which shows the outline of a structure in a reduced pressure drying apparatus. In FIG. 1A, the illustration of a structure for supporting a solvent collecting unit described later is omitted, and the illustration of a top plate described later is omitted in FIG. 1B. 2A and 2B are diagrams for explaining the mounting structure of the solvent collecting unit, FIG. 2A is a partial side view in the reduced pressure drying value, and FIG. 2B is a view of the solvent collecting unit in the reduced pressure drying apparatus. It is a surrounding partial bottom view.

The reduced-pressure drying apparatus according to this embodiment is for applying a solution applied onto a substrate by an ink-jet method and drying the solution in a reduced-pressure state. The substrate to be processed by this apparatus is, for example, a glass substrate for an organic EL display.
Note that the solution applied to the substrate to be processed of the present apparatus is composed of a solute and a solvent, and the components to be subjected to the vacuum drying process are mainly solvents. Many organic compounds contained in the solvent have a high boiling point. For example, 1,3-dimethyl-2-imidazolidinone (boiling point 220 ° C., melting point 8 ° C.), 4 -Tert-Butylanisole (4-tert-Butylanisole, boiling point 222 ° C, melting point 18 ° C), Trans-Anethole (Trans-Anethole, boiling point 235 ° C, melting point 20 ° C), 1,2-dimethoxybenzene (1,2-Dimethoxybenzene) , Boiling point 206.7 ° C., melting point 22.5 ° C., 2-methoxybiphenyl (boiling point 274 ° C., melting point 28 ° C.), phenyl ether (Phenyl Ether, boiling point 258.3 ° C., melting point 28 ° C.), 2-ethoxynaphthalene (2- Ethoxynaphthalene, boiling point 282 ° C., melting point 35 ° C., benzyl phenyl ether (Benzyl Phenyl Ether, boiling point 288 ° C., melting point 39 ° C.), 2,6-dimethoxytoluene (2,6-Dimethoxytoluene, boiling point 222 ° C., melting point 39 ° C.), 2-Propoxynaphthalene, boiling point 305 ℃, melting point 40 ℃), 1,2,3-trimethoxybenzene (1,2,3-Trimethoxybenzene, boiling point 235 ℃, melting point 45 ℃), cyclohexylbenzene (cyclohexylbenzene, boiling point 237.5 ℃, melting point 5 ℃), dodecylbenzene (Dodecylbenzene, boiling point 288 ° C., melting point −7 ° C.), 1,2,3,4-tetramethylbenzene (1,2,3,4-tetramethylbenzene, boiling point 203 ° C., melting point 76 ° C.) and the like. These high boiling point organic compounds may be combined in a solution in a combination of two or more.

  As shown in FIG. 1, the vacuum drying apparatus according to the present embodiment includes a chamber 10, a mounting table 20, and a solvent collection unit 30, and is connected to an exhaust device 40.

  The chamber 10 is configured to be airtight and is formed from a metal material such as stainless steel. The chamber 10 includes a rectangular tube-shaped main body 11, a top plate 12 attached to the upper side of the main body 11, and a bottom plate 13 attached to the lower side of the main body 11.

The main body 11 is provided with a loading / unloading port (not shown) for loading / unloading the substrate W into / from the chamber 10.
The top plate 12 closes the upper opening of the main body 11 and supports the solvent collection unit 30. The support structure of the solvent collection unit 30 will be described later.

  The bottom plate 13 closes the lower opening of the main body 11, and a mounting table 20 is disposed at the upper center of the bottom plate 13. Further, the bottom plate 13 is provided with an exhaust slit 13 a so as to surround the outer periphery of the mounting table 20, and an exhaust device 40 is connected to the exhaust port slit 13 a through an exhaust pipe 41. The inside of the chamber 10 of the vacuum drying apparatus 1 can be depressurized through the exhaust slit 13a.

  The mounting table 20 is used for mounting the substrate W thereon. The mounting table 20 is provided with a lifting pin (not shown) for transferring the substrate W, and the lifting pin can be freely moved up and down by a lifting mechanism.

  The solvent collection unit 30 collects the solvent evaporated from the solution applied on the substrate W by the inkjet method, and adjusts the solvent concentration in the atmosphere in the chamber 10.

The solvent collection unit 30 includes a solvent collection plate (hereinafter referred to as a solvent collection network) 31 formed of a thin plate having a shape in which openings are uniformly formed in a lattice shape, that is, a net-like plate.
The solvent collection net 31 is formed from a material having good thermal conductivity such as a metal material such as stainless steel, aluminum, copper, or gold. More specifically, for example, the solvent collection net 31 is made of expanded metal produced by cold-cutting a steel plate. Although the solvent collection net | network 31 may be comprised from one sheet of expanded metal, in this example, a plurality of sheets of expanded metal shall be arranged in the horizontal direction.

  The thickness of the solvent collection net 31 is, for example, 0.1 mm. The horizontal dimension of the solvent collection net 31 is substantially the same as the horizontal dimension of the substrate W. More specifically, the horizontal dimension of the plurality of expanded metals constituting the solvent collection net 31 is substantially the same as the horizontal dimension of the substrate W. However, the horizontal dimension of the solvent collection net 31 may be larger than the horizontal dimension of the substrate W in order to increase the adsorption amount of the evaporated solvent. Further, the horizontal dimension of the solvent collection network 31 is such that when the solvent collection network 31 is installed at the upper center of the substrate W, the balance of the vapor concentration in the chamber 10 is controlled. You may make it smaller than the dimension of a horizontal direction.

  The aperture ratio of the solvent collection network 31 is large, for example, 65%. The aperture ratio is given by (total area of opening of solvent collection network 31 in top view) / (total area of solvent collection network 31 in top view).

Since the solvent collection net 31 has a net shape with a large aperture ratio and is thin as described above, the heat capacity per 1 m ² is as low as 372 J / K, that is, the heat capacity per unit area is 372 J / K · m, for example. ² is low.

  The solvent collection net 31 is a structure on the upper side of the solvent collection net 31 and is supported at a position between the top plate 12 and the substrate W closest to the solvent collection net 31. The solvent collection net 31 is supported by the top plate 12 so as to face the substrate W, that is, substantially parallel to the substrate W.

As shown in FIG. 2, the support plate 31 is supported by the top plate 12 via a frame 32 and legs 33. This will be specifically described below.
Each of the expanded metals 31a constituting the solvent collection net 31 is fixed to a rectangular tube frame 32 by welding or the like. By fixing the ear 32a provided on the outside of the frame 32 to a leg 33 extending downward from the top 12 using screws or the like, the expanded metal 31a, that is, the solvent collection net 31 is attached to the top. Supported by the plate 12.
The frame body 32 and the leg portion 33 are made of a metal material such as stainless steel.
Further, the frame body 32 and the leg portion 33 are located on the opposite side of the substrate W with the solvent collection net 31 in between. Accordingly, since the entire surface of the solvent collection net 31 is uniformly exposed on the substrate W side, the flow of the vaporized solvent from the substrate W toward the solvent collection net 31 is in the frame body 32 and the legs 33. Not disturbed. However, in order to make the flow of the vaporized solvent more uniform, it is preferable that the volume of the frame body 32 and the leg portion 33 is small.

Returning to the description of FIG.
The exhaust device 40 is configured by a vacuum pump, and specifically, a turbo molecular pump and a dry pump are connected in series in this order from the upstream side, for example. The exhaust device 40 is disposed near the center of the bottom plate 13, that is, below the center of the substrate W.
An automatic pressure control valve (APC (Adaptive Pressure Control) valve) 42 is provided at a portion between the exhaust port slit 13 a of the exhaust pipe 41 and the exhaust device 40. In the vacuum drying apparatus 1, the degree of vacuum in the chamber 10 during vacuum exhaust can be controlled by adjusting the opening degree of the APC valve 42 while the vacuum pump of the exhaust apparatus 40 is operated.

  The vacuum drying apparatus 1 includes a pressure gauge (not shown) that measures the pressure in the chamber 10. The measurement result of the pressure gauge is input to the APC valve 42 as an electrical signal.

  The vacuum drying apparatus 1 includes a control unit (not shown) of the apparatus 1. The control unit is, for example, a computer and has a program storage unit (not shown). The program storage unit stores a program for controlling the reduced pressure drying process in the reduced pressure drying apparatus 1. The above program is recorded in a computer-readable storage medium such as a computer-readable hard disk (HD), flexible disk (FD), compact disk (CD), magnetic optical desk (MO), or memory card. Or installed in the control unit from the storage medium.

  Subsequently, the vacuum drying process using the vacuum drying apparatus 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is an explanatory diagram of the reduced-pressure drying process, and FIGS. 3A to 3D are diagrams illustrating the inside of the chamber 10 in each step of the reduced-pressure drying process. FIG. 4 is a diagram showing a vapor pressure curve of the solvent of the solution applied to the substrate W, where the horizontal axis represents temperature and the vertical axis represents pressure.

In the reduced-pressure drying process using the reduced-pressure drying apparatus 1, first, the substrate W on which the processing liquid is applied is placed on the mounting table 20 by an inkjet method. In this state, as shown in FIG. 3A, the temperature of the substrate W and the temperature of the solvent collection network 31 are both 23 ° C., which is room temperature. Further, the pressure in the chamber 10 at the time when the substrate W is placed on the placement table 20 is atmospheric pressure (about 10 × 10 ⁴ Pa), and the temperature of the substrate W is 23 ° C. as shown in FIG. The evaporation rate of the solvent S from the substrate W is small because it is larger than the saturated vapor pressure of the solvent S in FIG.

Next, the exhaust pump 40 is operated to evacuate the chamber 10 under reduced pressure. The vacuum exhaust by the dry pump is performed until the pressure in the chamber 10 becomes 10 Pa.
During this vacuum exhaust, the gas in the chamber 10 is cooled by adiabatic expansion. Even when the gas in the chamber 10 is cooled in this way, the temperature of the substrate W hardly changes from 23 ° C. at room temperature because the heat capacity of the substrate W is large. However, the temperature of the solvent collection net 31 having a small heat capacity decreases. Specifically, at the time when the vacuum exhaust with the dry pump is completed and the pressure in the chamber 10 reaches 10 Pa, the temperature of the solvent collection network 31 is, for example, 8 to 15 ° C. as shown in FIG. To fall.
As indicated by a point P1 in FIG. 4, the pressure 10 Pa in the chamber 10 at the end of the vacuum pumping at the dry pump is larger than the saturated vapor pressure of the solvent S at 23 ° C. that is the temperature of the substrate W. The evaporation rate is not large even at the end of the decompression exhaust.

  After the pressure in the chamber 10 is reduced to 10 Pa by the dry pump of the exhaust device 40, the turbo molecular pump of the exhaust device 40 is operated to further reduce the pressure.

  When the pressure in the chamber 10 becomes 0.2 Pa or less, which is the vapor pressure of the solvent at 23 ° C., which is the temperature of the substrate W, as shown by a point P2 in FIG. The evaporation rate increases.

At this time, the solvent collection network 31 is cooled along with the vacuum exhaust as described above, and when the pressure in the chamber 10 is reduced to 0.2 Pa, the temperature of the solvent collection network 31 is, for example, FIG. It is 8-15 degreeC as shown to (C). As is apparent from point P3 in FIG. 4, this 8 to 15 ° C. is smaller than 23 ° C., which is the dew point of the solvent at 0.2 Pa.
Further, the temperature of the solvent collection network 31 is maintained below the dew point of the solvent S at the pressure in the chamber 10 at each time until the evaporation of the solvent S on the substrate W is completed.

  Therefore, since the solvent evaporated from the substrate W is collected with high efficiency by the solvent collection network 31, the concentration of the gaseous solvent in the chamber 10 is kept low. Therefore, the solvent on the substrate W can be removed quickly.

  Even after the removal of the solvent S on the substrate W is completed, the exhaust by the turbo molecular pump of the exhaust device 40 is continued. This is because the solvent collected by the solvent collection network 31 is removed from the solvent collection network 31.

  If exhaustion by the turbo molecular pump is continued as described above, the temperature of the solvent collection network 31 having a small heat capacity increases due to radiant heat from the top plate 12 and the substrate W of the chamber 10. Specifically, within 5 minutes after the evaporation of the solvent S on the substrate W is completed, as shown in the point P4 of FIG. 4 and FIG. The temperature rises to 18 to 23 ° C. which is equal to or higher than the dew point of the solvent at the pressure (0.05 Pa) in the chamber 10. Therefore, the solvent can be quickly removed / desorbed from the solvent collection network 31.

The time from the completion of the evaporation of the solvent S on the substrate W until the temperature of the solvent collection network 31 becomes equal to or higher than the dew point of the solvent at the pressure of the chamber 10 at that time is preferably within 5 minutes. . This is because if it is longer than 5 minutes, it takes a long time to complete the desorption of the solvent from the solvent collection network 31, and the tact time becomes longer.
In addition, the time from the completion of the evaporation of the solvent S on the substrate W until the temperature of the solvent collection network 31 becomes equal to or higher than the dew point of the solvent at the pressure of the chamber 10 at that time is preferably 20 seconds or more. . Since the solvent S on the substrate W is completely dried in about 10 seconds from the start of evaporation, the solvent collection network 31 is preferably dried gradually over at least 10 seconds, preferably over 20 seconds. When the time is shorter than 20 seconds, when the solvent adsorbed on the solvent collection network 31 is vaporized, the vaporized solvent dissolves the dried coating film on the substrate W, or the vaporized solvent is adsorbed on the substrate W. This is because there is a risk of it.

  By continuing the exhaust with the turbo molecular pump until a predetermined time has elapsed after the temperature of the solvent collection network 31 becomes equal to or higher than the dew point of the solvent at the current pressure of the chamber 10 as described above, the solvent collection is performed. The drying process of the solvent collection net 31 for removing the solvent from the net 31 is completed.

  After the drying process of the solvent collection net 31 is completed, the exhaust device 40 is stopped. Thereafter, after returning the pressure in the chamber 10 to atmospheric pressure, the substrate W is unloaded from the chamber 10. Thus, the vacuum drying process in the vacuum drying apparatus 1 is completed.

  As described above, in the reduced pressure drying apparatus 1, since the mesh plate having a small heat capacity is used for the solvent collecting unit 30, it is not necessary to provide a separate mechanism for cooling / heating the solvent collecting unit 30 during the reduced pressure drying process. Therefore, in the reduced-pressure drying apparatus 1, the processing time including both the time required for drying the substrate (hereinafter, drying time) and the drying time of the solvent collection network 31 can be shortened with a simple configuration. In other words, the drying process of the solvent on the substrate and the desorption process of the solvent from the solvent collection unit 30 can be performed in a short time with a simple configuration.

Further, in the reduced pressure drying apparatus 1, in order to further shorten the drying time of the substrate, as described above, the temperature of the solvent collection network 31 is such that the pressure in the chamber 10 is equal to or lower than the temperature of the substrate W, that is, the vapor pressure at room temperature. At that time, the dew point at the pressure at that time, that is, the room temperature or less, and further, below the dew point at the pressure at each time until the evaporation is completed.
Furthermore, in the vacuum drying apparatus 1, in order to further shorten the drying time of the solvent collection network 31, as described above, the temperature of the solvent collection network 31 is within 5 minutes from the time when evaporation is completed. More than the dew point at the pressure.

The substrate drying time is preferably uniform within the same substrate. When the solvent collection net 31 is not provided, the drying time of the substrate W is not uniform within the same substrate, and the drying time is shorter at the corner than the center of the substrate W. Therefore, the dried corner may be dissolved by the solvent evaporated at the center thereafter.
In the vacuum drying apparatus 1, by providing the solvent collection network 31, the drying time becomes uniform within the same substrate W.

  A mechanism in which the drying time in the reduced-pressure drying apparatus 1 is uniform in the same substrate W will be described with reference to FIG. FIG. 5 is a diagram showing the inside of the chamber 10 of the vacuum drying apparatus 1, and FIGS. 5A and 5B respectively show the case where the solvent collection network 31 is not provided and the case where it is provided. FIG. Each gray line in the chamber 10 in FIG. 5 is an isoconcentration line, and the thicker the line, the higher the density. In the following description, if the concentration is the same, the evaporation rate is the same regardless of the location in the substrate W, and the temperature of the solvent collection network 31 is uniform regardless of the location in the network 31. And

According to Fick's first law, the diffusion flow rate is proportional to the concentration gradient.
When the solvent collection network 31 is not provided, the concentration gradient in the vertical direction is not uniform in the upper surface of the substrate W. For this reason, the diffusion flow velocity at the upper portion of the substrate W becomes non-uniform in the substrate W plane. Therefore, as shown in FIG. 5A, the concentration of the gaseous solvent is not uniform in the upper part of the substrate W, and the drying time varies in the same substrate W.

  On the other hand, when the solvent collection network 31 is provided so as to face the substrate W, the concentration gradient in the vertical direction is uniform in the upper surface of the substrate W in the chamber 10. Therefore, the diffusion flow velocity is uniform in the substrate W plane above the substrate W. Therefore, as shown in FIG. 5B, the concentration of the solvent on the substrate is uniform above the substrate W, and the drying time is uniform in the same substrate W.

Next, the solvent collection net 31 of the solvent collection unit 30 will be described in detail.
In the above description, the solvent collection net 31 has a heat capacity per unit area of, for example, 372 J / K · m ² . However, the heat capacity per unit area of the solvent collection network 31 is not limited to that described above, and the temperature of the solvent collection network 31 decreases due to adiabatic expansion in the chamber 10 due to exhaust, and radiant heat from the chamber 10 and the like. The temperature of the solvent collection net 31 only needs to rise. Therefore, the heat capacity per unit area of the solvent collection net 31 may be 106 to 850 J / K · m ² or less. In addition, when the plate thickness of the solvent collection net 31 is 0.05 mm and the aperture ratio is 80%, the heat capacity per unit area is 106 J / K · m ² , and the plate thickness of the solvent collection net 31 is 0.2 mm. The heat capacity per unit area when the aperture ratio is 60% is 850 J / K · m ² .

  Moreover, the solvent collection net | network 31 is supported by the position between the board | substrate W and the top plate 12 as mentioned above. More specifically, the position where the distance from the upper surface of the substrate W to the center in the thickness direction of the solvent collection network 31 is 40 to 60% of the distance from the upper surface of the substrate W to the lower surface of the top plate 12 of the chamber 10. Supported by The gas expansion rate during decompression, that is, the cooling strength due to adiabatic expansion, differs depending on the position in the vertical direction, and is larger than the other locations at the position of 40 to 60% described above. Therefore, the solvent collection network 31 can be greatly cooled by supporting at this position, and heating by radiant heat from the chamber 10 to the solvent collection network 31 under vacuum does not depend on the distance between them. Therefore, the solvent from the substrate W can be removed quickly.

FIG. 6 is a cross-sectional view for explaining a suitable processing method for the mesh plate constituting the solvent collection net 31.
As described above, the net-like solvent collection net 31 is made of expanded metal processed by a cold drawing method. Therefore, as shown in FIG. 6 (A), the solvent collection net 31 has a quadrangular shape in the longitudinal section, and the upper and lower surfaces are flat.

  On the other hand, when the net-like solvent collection net 31 is formed by weaving the wire R as shown in FIG. 6B, the wire R has a cylindrical cross section. Further, the portion where the wire R overlaps due to weaving is shaded. Therefore, in the case of the above-mentioned weaving, radiation from the upper and lower sides cannot be obtained uniformly, so that the temperature of the solvent collection net 31 does not easily rise. Therefore, it takes a long time to remove the solvent from the solvent collection network 31. Furthermore, when the wire R is knitted, particles are likely to be generated due to rubbing of the contact portion between the wires R.

  Further, as shown in FIG. 6C, when the solvent collection net 31 is formed in a net shape by punching a flat plate to form an opening H, the upper and lower surfaces are not flat in the longitudinal section. For this reason, the solvent collection network 31 is less susceptible to radiant heat from the top plate of the chamber 10, and it takes a long time to remove the solvent from the solvent collection network 31. In addition, when processing is performed by punching, dust is likely to adhere because a point is formed. Furthermore, when the opening H is formed by punching, since the opening ratio cannot be increased, it is difficult for the air flow caused by evacuation to pass while diffusing through the solvent collection network 31 during cooling. Even if it is cooled, its effect is difficult to obtain.

However, when the solvent collection net 31 is made of expanded metal, as described above, it is square in the longitudinal section and flat on the top and bottom surfaces. Therefore, the solvent collection network 31 made of expanded metal can easily remove the adsorbed solvent in a short time because the solvent collection network 31 is susceptible to radiant heat from the top plate of the chamber 10. Moreover, when comprised with an expanded metal, a cusp is not formed and dust does not adhere. Further, since there is no rubbing as in the case of wire braiding, no particles are generated. Furthermore, since the opening ratio can be increased in the expanded metal, the solvent can be collected with high efficiency when cooled.
In addition, the solvent collection net | network 31 is not restricted to the expanded metal produced by the cold drawing method, If it is produced by the method of cutting and expanding it to a flat plate, it can use suitably.

  The thickness of the solvent collection net 31 is 0.1 mm in the above description, but may be 0.05 mm or more and 0.2 mm or less. If the thickness is 0.05 mm or more, it can be easily processed, and by setting the thickness to 0.2 mm or less, the heat capacity per unit area can be suppressed and the adsorption rate of the solvent can be increased. .

  Moreover, although the aperture ratio of the solvent collection net | network 31 was 65% in the above-mentioned description, it should just be 60% or more and 80% or less. If the opening ratio is 60% or more, the solvent collection efficiency in the solvent collection network 31 can be increased, and if the opening ratio is 80% or less, it can be easily processed.

(Second Embodiment)
FIG. 7 is a longitudinal sectional view showing a schematic configuration of a reduced pressure drying apparatus according to the second embodiment of the present invention.
The vacuum drying apparatus 1 in FIG. 7 includes an infrared radiator 50.
The infrared radiator 50 is a plate-like member and is provided on the lower surface side of the top plate 12 of the chamber 10 so as to face the solvent collection net 31. The infrared radiator 50 radiates infrared rays and heats the solvent collection net 31 that has a lower temperature than the infrared radiator 50.
By providing this infrared radiator 50, the solvent adsorbed on the solvent collection network 31 can be removed quickly.

  The infrared radiator 50 has a heater inside, and when the solvent is evaporated from the substrate, the heater is turned off so that the solvent collection net 31 is not heated by the infrared radiator 50. In addition, providing the heater in the infrared radiator 50 can be performed more easily than providing the similar heater in the solvent collection network 31, and if the similar heater is provided directly in the solvent collection network 31. This is because the heat capacity of the solvent collection unit 30 increases and the solvent collection network 31 accompanying the vacuum exhaust cannot be cooled.

  The infrared radiator 50 is not limited to a plate-like member, and may be, for example, a cylindrical member. Further, in order to cause the infrared radiator 50 to act as a black body, the infrared radiator 50 may be subjected to blackening treatment. The blackening process is a process of applying a black body paint, for example, and includes a process of forming the infrared radiator 50 itself with a black body material. In the case of a black body material, since the emissivity is large even without a heater, the effect of heating the solvent collection net 31 is improved.

(Third embodiment)
FIG. 8 is a diagram showing a schematic configuration of a reduced-pressure drying apparatus according to the third embodiment of the present invention. FIG. 8A is a sectional view showing an outline of the configuration of the reduced-pressure drying apparatus, and FIG. It is a top view which shows the outline of a structure in a drying apparatus. In FIG. 8 (A), illustration of the structure for supporting the solvent collection part 30 is abbreviate | omitted, and illustration of the top plate 12 grade | etc., Is abbreviate | omitted in FIG. 8 (B).

  The bottom plate 60 of the vacuum drying apparatus 1 in FIG. 8 closes the lower opening of the main body 11, and the mounting table 20 is disposed on the upper side of the bottom plate 60. The bottom plate 60 is provided with a plurality of openings 60 a on the outer periphery of the mounting table 20. In this example, three openings 60a are provided along one side of the mounting table 20, and three openings 60a are provided along the side opposite to the one side.

An exhaust device 62 is connected to the opening 60 a via an exhaust pipe 61. The inside of the chamber 10 of the reduced pressure drying apparatus 1 can be depressurized through the opening 60a.
The exhaust device 62 is composed of a vacuum pump. Specifically, a turbo molecular pump and a dry pump are connected in series in this order from the upstream side, for example. One exhaust device 62 is provided for each opening 60a.
The exhaust pipe 61 is provided with an APC valve 42.

  Further, the reduced pressure drying apparatus 1 of the present embodiment includes another solvent collection unit 70 for drying the solvent collection unit 30, and the other solvent collection unit 70 is temporarily provided in the solvent collection unit 30. The solvent vaporized after being collected in the chamber is temporarily collected, and the solvent in the chamber 10 is withered. Hereinafter, this another solvent collection unit 70 may be referred to as a withering collection unit 70, and the solvent collection unit 30 may be referred to as a substrate drying collection unit 30. The withering collection unit 70 is temporarily set to the substrate drying collection unit 30 by being set to a temperature lower than that of the substrate drying collection unit 30 after the evaporation of the solvent of the solution on the substrate W is completed. It is possible to temporarily collect the solvent which has been vaporized after being collected in the catalyst. The withering collection unit 70 is different in size and shape from the substrate drying collection unit 30, but the same material as the substrate drying collection unit 30 may be used as the material, for example, the substrate drying collection unit. Similar to the unit 30, it has a solvent collection net (not shown) composed of a net-like plate.

  The withering collection unit 70 is provided in a space from the substrate drying collection unit 30 to each exhaust device 62. Specifically, the withering collection unit 70 is an APC valve as a closing member that can be freely opened and closed between the space in which the substrate drying collection unit 30 is disposed and the space in which the exhaust device 62 is disposed. 42 is provided downstream of 42. More specifically, the withering collection unit 70 is provided downstream of the APC valve 42 in the exhaust pipe 61.

Then, the reduced pressure drying process using the reduced pressure drying apparatus 1 of this embodiment is demonstrated.
Among the reduced-pressure drying processes using the reduced-pressure drying apparatus 1 of the present embodiment, the processes up to the drying process of the substrate W are the same as those of the drying / decompression process using the reduced-pressure drying apparatus 1 of the first embodiment. The description is omitted.
In the reduced-pressure drying process using the reduced-pressure drying apparatus 1 according to the present embodiment, the gas in the chamber 10 is exhausted under reduced pressure during the drying process of the substrate W, as in the first embodiment. Is adiabatically expanded and cooled. Due to the gas in the chamber 10 thus cooled, the temperatures of the substrate drying collection unit 30 and the withering collection unit 70 are lowered. At this time, the withering collection unit 70 has a lower flow rate per unit area of the cooled gas than the surroundings of the substrate drying collection unit 30 at a lower temperature than the substrate drying collection unit 30. It becomes.

The solvent vaporized from the substrate W has a lower temperature in the withering collection unit 70 than the substrate drying collection unit 30, but the withering collection unit 70 is farther from the substrate W. Collected by the unit 30.
Even after the solvent vaporized from the substrate W is collected by the substrate drying collection unit 30 and the removal of the solvent on the substrate W is completed, the exhaust by the turbo molecular pump of the exhaust device 62 is continued. This is because the solvent collected by the substrate drying collection unit 30 is removed from the collection unit 30 to dry the collection unit 30. At the time of this drying, the withering collector 70 has a lower temperature than the substrate drying collector 30, so that the solvent evaporated from the substrate drying collector 30 is collected by the withering collector 70. Therefore, the concentration of the gaseous solvent around the substrate drying collection unit 30 is kept low. Therefore, the solvent on the substrate drying collection unit 30 can be quickly removed and dried.

  As described above, when the evacuation by the turbo molecular pump is continued even after the removal of the solvent on the substrate W is completed as described above, as described in the first embodiment, the substrate drying collection unit 30 Although the temperature rises due to radiant heat from the top plate 12 and the substrate W of the chamber 10, the withering collection unit 70 is farther from the top plate 12 and the substrate W and the like than the collection unit 30 for drying the substrate. The temperature rise due to the radiant heat is moderate. Accordingly, since the temperature difference between the withering collection unit 70 and the substrate drying collection unit 30 is widened, the solvent can be quickly removed / desorbed from the substrate drying collection unit 30.

  The drying process of the substrate drying collection unit 30 that removes the solvent from the substrate drying collection unit 30 is terminated, for example, by performing exhaustion by a turbo molecular pump of the exhaust device 62 for a predetermined time.

After the drying process of the substrate drying collection unit 30 is completed, the APC valve 42 is closed. Thereby, the space where the substrate W in the chamber 10 exists and the space where the collection part 70 for withering exist can be isolated.
Then, a carry-in / out process for purging the inside of the chamber 10 and carrying in / out the substrate W and a drying process for drying the collection part 70 for withering are performed in parallel. By performing in parallel in this way, the time required for the entire vacuum drying process using the vacuum drying apparatus 1 of the present embodiment can be greatly shortened.

  The withering collection unit 70 is disposed in the exhaust pipe 61 so as to be heated by radiant heat from the turbo molecular pump of the exhaust device 62. Thereby, since the vaporization of the solvent from the collection part 70 for withering can be promoted, the time until the drying of the collection part 70 for withering is completed can be shortened. By the time it is completed, the drying of the withering collection unit 70 can be reliably completed. Further, since radiant heat from the turbo molecular pump of the exhaust device 62 is used, there is no need for a separate means for heating the collection part 70 for withering, so that the configuration of the vacuum dryer 1 is complicated and the vacuum dryer 1 is large. Can be prevented.

(Fourth embodiment)
FIG. 9 is a diagram showing a schematic configuration of a vacuum drying apparatus according to the fourth embodiment of the present invention, and shows a partial cross section of the vacuum drying apparatus.

In the above example, the APC valve 42 is used as the “blocking member” according to the present invention. However, when it is not necessary to accurately adjust the pressure in the chamber 10 of the vacuum drying apparatus 1, the “blocking member” Another can be used.
In the reduced-pressure drying apparatus 1 of FIG. 9, as the “blocking member”, a blocking member 80 having a shutter 81 that opens and closes between the mounting table 20 and the side wall 11 a of the chamber 10 by a hinge type, for example, can be opened and closed. ing. By using the closing member 80, the reduced-pressure drying apparatus 1 can be manufactured at a lower cost than when the APC valve 42 is used.

  Further, in the third embodiment, the APC valve 42 as a closing member is provided in the exhaust pipe 61, but in this embodiment, the closing member 80 is provided in the chamber 10. Therefore, it is possible to dispose the collection part 70 for withering, which should be arranged downstream of the closing member, in the chamber 10, that is, the collection part 30 for drying the substrate as compared with the third embodiment. It can be arranged nearby. When the withering collection unit 70 is disposed near the substrate drying collection unit 30, the solvent vaporized from the substrate drying collection unit 30 can be efficiently collected by the withering collection unit 70.

  Furthermore, the withering collection portion 70 is provided so that the surface thereof is horizontal in the third embodiment, but in this embodiment, the collection portion 70 is tilted so that the surface thereof is non-horizontal and non-vertical. Is provided. A tray 91 is provided on the bottom plate 90 below the lowermost part of the collecting part 70 for withering. The tray 91 receives the solvent that has been collected by the collection part 70 for withering and becomes a liquid, and the solvent that has become the liquid follows the inclined surface / inclined surface of the collection part 70 for withering. And then falls from the lowermost part of the collection part 70 to the tray part 91.

  The liquid solvent received by the tray 91 is vaporized and discharged from the chamber 10 by the exhaust device 62. In such a configuration, the saucer 91 can be heated by a heating mechanism that heats the saucer 91, and therefore, the vaporization of the liquid solvent received by the saucer 91 can be promoted. The solvent in the chamber 10 can be quickly discharged out of the chamber 10.

(Fifth embodiment)
FIG. 10 is a diagram showing a schematic configuration of a vacuum drying apparatus according to the fifth embodiment of the present invention, and shows a partial cross section of the vacuum drying apparatus.

In the vacuum drying apparatus 1 of FIG. 10, a closing member 100 having a shutter 101 that opens and closes between the mounting table 20 and the top plate 12 of the chamber 10 is provided in the chamber 10 as a “closing member”. The shutter 101 moves in the vertical direction, that is, moves up and down, thereby closing the space between the mounting table 20 and the top plate 12 of the chamber 10 so as to be freely opened and closed. By using the closing member 100, the following effects are obtained in addition to the same effects as those of the fourth embodiment.
That is, in the configuration using the closing member 100, at least a part of the withering collection unit 70 can be positioned above the upper surface of the mounting table 20. Therefore, since the withering collection unit 70 and the substrate drying collection unit 30 are close to each other, the solvent evaporated from the substrate drying collection unit 30 can be efficiently collected by the withering collection unit 70. .

  Moreover, in this embodiment, this withering collection part 70 can be arrange | positioned so that the withering collection part 70 may be extended in a perpendicular direction. Therefore, the present embodiment can reduce the distance between the side wall 11a of the chamber 10 and the mounting table 20 as compared with the fourth embodiment, that is, the chamber 10 can be prevented from being enlarged.

In the fourth and fifth embodiments, the withering collection unit 70 is arranged to be heated by radiant heat from the turbo molecular pump of the exhaust device 62.
9 and 10, the exhaust pipe 61 communicating with the exhaust device 62 is provided on the side wall 11a of the chamber 10, but may be provided on the bottom plate 90. However, by providing the exhaust device 62 on the side wall 11a, even if a large amount of the solvent accumulated in the collection part 70 for withering falls as a droplet, the droplet does not enter the exhaust device 62. Therefore, the risk of damage to the exhaust device 62 can be greatly reduced.

It should be noted that the heating mechanism for heating the tray portion 91 can be performed very easily as compared with the case where a similar heating mechanism is provided in the substrate drying collection unit 30.
In addition, the opening and closing of the shutters 81 and 101 in the fourth and fifth embodiments is controlled by the above-described control unit of the vacuum drying apparatus 1.
In addition, since the reduced pressure drying process using the reduced pressure drying apparatus 1 of 4th and 5th embodiment is substantially the same as the reduced pressure drying process which concerns on 3rd Embodiment, the description is abbreviate | omitted.

  In the above description, the drying process of the withering collection unit 70 and the carry-in / out process of the substrate W are performed simultaneously. However, after the drying process of the withering collection unit 70 is completed, the carry-in / out process of the substrate W is performed. May be. In this case, it is not necessary to provide the withering collecting part 70 on the downstream side of the closing member such as the APC valve 42, and the withering collecting part 70 may be provided on the upstream side of the closing member. In addition, even in the case of being provided on the upstream side in this way, the closing member and the withering collecting unit 70 are arranged near the turbo molecular pump of the exhaust device 62, and the withering collecting unit 70 is heated by the radiant heat from the pump. The solvent collected in the collection unit 70 is quickly vaporized and removed.

  In addition, in order to quickly collect the solvent in the collection part 70 for withering and quickly vaporize and remove the solvent collected in the collection part 70 for withering, the configuration of the vacuum drying apparatus 1 is not complicated. A cooling mechanism or a heating mechanism may be incorporated in the withering collection unit 70.

(First Reference Embodiment)
FIG. 11 is a longitudinal sectional view showing a schematic configuration of the vacuum drying apparatus according to the first reference embodiment. In addition, in this figure, about the collection part for withering, only the position in which this collection part is provided is shown.
In the third to fifth embodiments, the withering collection unit 70 basically has no cooling / heating mechanism for cooling and / or cooling the collection unit 70. The reduced-pressure drying apparatus 200 in FIG. 11 according to the embodiment has a cooling and heating mechanism in which the withering collection unit 210 cools and heats the collection unit 210.

  FIG. 12 is a longitudinal sectional view for explaining an example of the withering collection unit 210 having a cooling and heating mechanism.

  The cooling heating mechanism of the withering collection unit 210 in FIG. 12A includes a plurality of refrigerant pipes 211 that can flow the cooled refrigerant and the heated refrigerant in a switchable manner. Each refrigerant pipe 211 is made of a material having good thermal conductivity, and is made of, for example, copper. The plurality of refrigerant pipes 211 are arranged in a mountain shape with the center being higher in a side view, and a metal plate 212 for collecting the solvent is fixed to the upper part of each refrigerant pipe 211 by welding or the like. . The plates 212 are partially overlapped with each other and tilted non-horizontally in a fixed state so that the solvent collected in the plate 212 and turned into a liquid flows outward along the plate 212. In this structure, although not shown, it is preferable to provide one tray portion (see reference numeral 91 in FIG. 9) having a heating mechanism one by one on the outer side of the withering collection portion 210.

  The cooling and heating mechanism of the withering collection unit 210 in FIG. 12B is arranged such that the plurality of refrigerant tubes 211 have a valley shape with a lower center in a side view. Each plate 212 fixed to the upper part of the refrigerant pipe 211 partially overlaps with each other so that the solvent that is collected in the plate 212 and becomes a liquid flows inward along the plate 212. It is tilted non-horizontally. In this structure, although not shown, it is preferable to provide one tray portion (see reference numeral 91 in FIG. 9) having a heating mechanism in the center of the withering collection portion 210.

  In the cooling and heating mechanism of the withering collector 210 in FIG. 12C, a plurality of refrigerant tubes 211 are arranged in parallel in a side view, and in this mechanism, the solvent is collected in the refrigerant tubes 211 and the liquid is collected. Become. Further, in this mechanism, a w-shaped side tray part 213 that receives the solvent collected in the refrigerant pipe 211 and becomes a liquid is fixed to the lower part of each refrigerant pipe 211 by welding or the like.

  In the cooling and heating mechanism of the withering collection portion 210 in FIG. 12D, a plurality of refrigerant tubes 211 are arranged in parallel in a side view, and a metal net member 214 is welded to the refrigerant tubes 211 by welding or the like. The solvent is collected by the mesh member 214 and the like.

(Second Reference Embodiment)
FIG. 13 is a longitudinal sectional view showing a schematic configuration of a reduced pressure drying apparatus according to the second reference embodiment.
In the vacuum drying apparatus 200 of FIG. 13, a refrigerant pipe 211 as a cooling and heating mechanism is wound around an exhaust pipe 61, and the exhaust pipe 61 functions as a collecting part 210 for withering.

In the above first and second reference embodiments, the withering collection part has a cooling and heating mechanism, so that the substrate drying collection part is quickly dried, and the withering collection part is quickly dried, The concentration of the solvent in the chamber can be quickly reduced to a desired value.
In the above example, the refrigerant pipe can switch between the cooled refrigerant and the heated refrigerant in a switchable manner, but may flow only one of them. Further, the cooling and heating mechanism may be one in which, for example, a refrigerant pipe for flowing the cooled refrigerant and a cooling pipe for flowing the heated refrigerant are alternately arranged.

(Third reference embodiment)
FIG. 14 is a longitudinal sectional view showing a schematic configuration of a reduced pressure drying apparatus according to the third reference embodiment.
The reduced-pressure drying apparatus 200 of FIG. 14 has a withering collection unit 210 having a cooling and heating mechanism and a substrate drying collection unit 220 having a cooling and heating mechanism. As the cooling and heating mechanism of the substrate drying collection unit 220, the same mechanism as used in the past can be employed. Also in this reduced pressure drying apparatus 200, the time required for the reduced pressure drying process can be greatly shortened.

  In the above description, the exhaust device has a turbo molecular pump. However, when the adsorption capacity of the collection part for withering is equivalent to the exhaust capability of the turbo molecular pump, the exhaust device has a configuration having only a dry pump. Even in this configuration, the time until the substrate drying is completed can be made the same as the configuration having the turbo molecular pump. When the exhaust device has only a dry pump, the temperature of the substrate W is heated by the mounting table 20 when the substrate W is dried, and the withering collecting portion 70 is provided downstream of the closing member. It is preferable to close the closing member after drying the substrate drying collection unit 30 and heat the withering collection unit 70.

(Other embodiments)
The vacuum drying apparatus according to the embodiment of the present invention preferably includes a temperature adjustment mechanism that adjusts the minimum temperature of the solvent collection network during vacuum exhaust by a method other than cooling or heating. By adjusting the minimum temperature of the solvent collection network during vacuum exhaust, the adsorption efficiency of the solvent to the solvent collection network, that is, the drying time of the substrate, and the time until the solvent from the solvent collection network is removed can be adjusted. Because.

  The above-described temperature adjusting mechanism is, for example, adjusting the opening speed of the dry pump by adjusting the opening degree of the APC valve (see reference numeral 42 in FIG. 1), thereby adjusting the minimum temperature of the solvent collection network. is there. However, the temperature adjustment mechanism is not limited to this form. For example, the cooling strength due to adiabatic expansion during evacuation is different depending on where the solvent collection network is located between the top plate of the chamber and the substrate. The minimum temperature of the solvent collection network may be adjusted by adjusting the elevating pin with a lifting pin provided on the mounting table. Further, a mechanism for adjusting the vertical position of the solvent collection network may be provided separately, and the minimum temperature of the solvent collection network may be adjusted by adjusting the vertical position.

Example 1 has the same structural member as the vacuum drying apparatus 1 in FIG. 1, and a vacuum drying process was performed on a 2200 mm × 2500 mm glass substrate coated with a solution by an ink jet method. Moreover, in Example 1, 12 pieces of 2200 mm × 200 mm expanded metal were used side by side as the solvent collection net 31 of the solvent collection unit 30. The material of the expanded metal is stainless steel (SUS316 BA), the net thickness is 0.1 mm, the aperture ratio is 65%, and the unit mass is 0.61 kg / m ² .
In Example 1, the solvent collection net 31 was supported at an intermediate position between the substrate W and the top plate 12 of the chamber 10. The support structure at that time has leg portions provided at both ends of the top plate 12 of the chamber 10, and has long support members (stays) provided on the respective leg portions and parallel to each other, Each expanded metal is fixed to the support member by screwing.
Further, in Example 1, the chamber 10 was evacuated by a dry pump until the pressure in the chamber 10 reached 10 Pa, and thereafter evacuated by a turbo molecular pump.

  The comparative example 1 did not have the solvent collection part 30, and it was the same as that of Example 1 except the structure which concerns on the solvent collection part 30. FIG.

  In Comparative Example 2, the member that collects the solvent is made of a punching metal like the solvent collection net 31. The horizontal dimension of the punching metal is the same as in Example 1, but the aperture ratio is 34% and the thickness is 0.2 mm. The volume of the solvent collecting member made of punching metal is 3.6, where the volume of the solvent collecting net 31 made of expanded metal is 1. That is, in Comparative Example 2, the heat capacity of the member for collecting the solvent was made larger than that in Example 1. The configurations of Comparative Example 2 and Example 1 are the same except for the configuration of the member that collects the solvent.

  In Comparative Example 1, the drying time of the substrate was 103 seconds near the center of the substrate and 92 seconds at the corner of the substrate.

  On the other hand, in Example 1, the drying time of the substrate was 71 seconds near the center of the substrate and 67 seconds at the corner of the substrate. Thus, in Example 1, compared with the comparative example 1, it was recognized that the drying time of a board | substrate becomes short and drying time becomes uniform in the same board | substrate. In Example 1, the minimum temperature of the central portion of the solvent collection net 31 during the drying process was 8 ° C.

  On the other hand, in the comparative example 2, the minimum temperature of the center part of the solvent collection member at the time of a drying process was 18 degreeC, and the fall from room temperature was recognized. However, the drying time and uniformity of the substrate were the same as those in Comparative Example 1. Thus, the adsorption effect by the solvent collecting member made of punching metal was not recognized.

15-17 is a figure which shows the time change of the temperature near the center of the solvent collection net | network 31 in Example 1, and the pressure in the chamber 10. FIG. 8 to 10, the horizontal axis represents time, and the vertical axis represents temperature or pressure.
As shown in FIG. 15, in Example 1, the temperature near the center of the solvent collection network 31 monotonously decreases to 8 ° C. due to adiabatic expansion accompanying decompression exhaust with a dry pump. Note that the pressure in the chamber 10 when the temperature reaches 8 ° C. is 2 × 10 ³ Pa.
Thereafter, the temperature near the center of the solvent collection network 31 increases from 8 ° C. due to radiant heat from the chamber 10 or the like. However, even after T1 when the pressure in the chamber 10 reaches the vapor pressure (0.2 Pa) of the solvent at the substrate temperature, that is, the room temperature, after switching from the vacuum exhaust with the dry pump to the vacuum exhaust with the turbo molecular pump. The temperature in the vicinity of the center of the solvent collection net 31 is a dew point at the pressure in the chamber 10 at the time point T1, that is, 14 ° C. below room temperature.

  Further, as shown in FIG. 16, the temperature near the center of the solvent collection network 31 is at each time point until the time point T2 at which the evaporation of the solvent on the substrate is completed, that is, until the pressure in the chamber 10 becomes 0.1 Pa. Is maintained below the dew point of the solvent S at the pressure in the chamber 10.

  While evaporation of the solvent S on the substrate W is completed and evacuation by the turbo molecular pump of the evacuation apparatus 40 is continued, the temperature near the center of the solvent collection network 31 is set in the chamber 10 as shown in FIG. It moves up and down by radiant heat from the top plate 12. However, at the time T3 220 seconds after the start of exhausting within 5 minutes after the evaporation of the solvent on the substrate is completed, the temperature of the solvent collection network 31 is the pressure (0.03 Pa) of the chamber 10 at the time T3. The temperature rises to 16 ° C., which is higher than the dew point (15 ° C.) of the solvent.

  FIG. 18 is a diagram illustrating a temporal change in temperature and a temporal change in pressure in the chamber 10 in each part of the solvent collection network 31 in the first embodiment. In the figure, the horizontal axis represents time, and the vertical axis represents temperature. In the following description, the vicinity of the center of the solvent collection network 31, the vicinity of the center of the long side portion, and the corners are portions indicated by points P11, P12, and P13 in FIG.

As shown in FIG. 18, the temperature near the center P11 of the solvent collection network 31 decreases as the pressure in the chamber 10 is reduced.
The temperature near the center P12 and the temperature of the corner portion P13 in the long side portion of the solvent collection net 31 also decrease as the pressure in the chamber 10 is reduced. It is smaller than the temperature near the center P11 of the mesh 31, and in particular, the temperature of the corner P13 is at least 17 ° C. As described above, the reason why the temperature of the solvent collection network 31 is not uniform is that, in the vicinity of the center P12 and the corner P13 in the long side portion, the expansion coefficient due to the decompression exhaust is small and the temperature is not easily lowered, and the exhaust conductance In view of the above, it is conceivable that the corner portion P13 is less likely to flow air that is expanded and cooled than the central portion P12 in the long side portion.

  As described above, when the temperature distribution of the solvent collection network 31 is a distribution in which the temperature near the center P11 is low and the corner portion P13 is high, the concentration of the gaseous solvent on the upper surface of the substrate to be vacuum dried is near the center of the substrate Therefore, it is considered that the central portion of the same substrate has a faster drying time than the corner portion, and the drying time is not uniform. However, in Example 1, the drying time is uniform as described above. Thus, the drying time becomes uniform because the drying time of the substrate is larger at the corner of the substrate than near the center of the substrate even when the concentration of the gaseous solvent on the upper surface of the substrate (the sky) is uniform. Because it is fast.

  The present invention is useful for a technique for drying under reduced pressure on a substrate coated with a solution by an inkjet method.

DESCRIPTION OF SYMBOLS 1 ... Vacuum drying apparatus 10 ... Chamber 11 ... Main-body part 12 ... Top plate 13 ... Bottom plate 13a ... Exhaust port slit 20 ... Mounting stand 30 ... Solvent collection part (collection part for board | substrate drying)
DESCRIPTION OF SYMBOLS 31 ... This solvent collection net 31 ... Solvent collection net 31a ... Expanded metal 32 ... Frame 32a ... Ear part 33 ... Leg part 40 ... Exhaust device 42 ... APC valve 50 ... Infrared radiator 50 ... Infrared radiator 70 ... Another solvent collector (withering collector)

Claims (21)

A vacuum drying apparatus for drying a solution on a substrate housed in a chamber in a vacuum state,
Comprising a net-like plate, and a solvent collecting part for temporarily collecting the solvent in the solution vaporized from the substrate,
The solvent collector is
Provided to face the substrate in the chamber;
When the pressure in the chamber is reduced below the vapor pressure of the solvent at the temperature of the substrate, the temperature of the solvent collecting unit is changed at that time by the gas in the chamber adiabatically expanded due to the reduced pressure. Cooled to below the dew point of the solvent at the chamber pressure of
Until the evaporation of the solvent of the solution on the substrate is completed, the temperature of the solvent collector is maintained below the dew point of the solvent at the pressure in the chamber at each time point,
Within 5 minutes after the evaporation of the solvent of the solution on the substrate is completed, the temperature of the solvent collecting part becomes equal to or higher than the dew point of the solvent at the pressure of the chamber at that time due to radiant heat from the chamber. A vacuum drying apparatus characterized by that. A vacuum drying apparatus for drying a solution on a substrate housed in a chamber in a vacuum state,
Comprising a net-like plate, and a solvent collecting part for temporarily collecting the solvent in the solution vaporized from the substrate,
The solvent collecting unit is provided to face the substrate in the chamber,
The net-like plate has an opening ratio of 60% or more and 80% or less, and a heat capacity per 1 m ² is 850 J / K or less.   The reduced-pressure drying apparatus according to claim 2, wherein the mesh plate has a thickness of 0.05 mm or more and 0.2 mm or less.   The reduced-pressure drying apparatus according to claim 2 or 3, wherein the mesh plate is an expanded metal produced by cold-cutting a metal plate.   The reduced-pressure drying apparatus according to any one of claims 2 to 4, wherein the mesh plate is made of stainless steel.   The distance from the said substrate to the said solvent collection part is 40% or more and 60% or less of the distance from the said substrate to the top plate of the said chamber, The any one of Claims 2-5 characterized by the above-mentioned. The vacuum drying apparatus as described.   The vacuum drying apparatus according to claim 2, wherein an infrared radiator is provided in the chamber. A vacuum drying apparatus for drying a solution on a substrate housed in a chamber in a vacuum state,
Comprising a net-like plate, and a solvent collecting part for temporarily collecting the solvent in the solution vaporized from the substrate,
The solvent collecting unit is provided to face the substrate in the chamber,
The reduced-pressure drying apparatus characterized in that the distance from the substrate to the solvent collecting unit is 40% or more and 60% or less of the distance from the substrate to the structure above the solvent collecting unit.   The reduced-pressure drying apparatus according to claim 8, wherein the mesh plate has a thickness of 0.05 mm or more and 0.2 mm or less.   The reduced-pressure drying apparatus according to claim 8 or 9, wherein the mesh plate is an expanded metal manufactured by cold-cutting a metal plate.   The vacuum drying apparatus according to any one of claims 8 to 10, wherein the mesh plate is made of stainless steel.   The reduced-pressure drying apparatus according to any one of claims 8 to 11, wherein an infrared radiator is provided in the chamber. Connected to an exhaust device for depressurizing the chamber;
Another solvent collection unit provided in a space from the solvent collection unit to the exhaust device,
The another solvent collector is at a lower temperature than the solvent collector, and temporarily collects the vaporized solvent after being temporarily collected by the solvent collector. The reduced-pressure drying apparatus according to any one of claims 1 to 12. A vacuum drying apparatus for drying a solution on a substrate housed in the chamber by bringing the chamber into a vacuum state with an exhaust device,
A solvent collecting part that is provided so as to face the substrate in the chamber and temporarily collects the solvent in the solution vaporized from the substrate;
Another solvent collection unit provided in a space from the solvent collection unit to the exhaust device,
The another solvent collector is at a lower temperature than the solvent collector, and temporarily collects the vaporized solvent after being temporarily collected by the solvent collector. A vacuum drying device.   The reduced-pressure drying apparatus according to claim 14, wherein the another solvent collection unit includes a cooling unit that cools the other solvent collection unit.   The reduced-pressure drying apparatus according to claim 14 or 15, wherein the another solvent collection unit includes a heating unit that heats the other solvent collection unit. The exhaust device has a turbo molecular pump,
The reduced-pressure drying apparatus according to claim 14, wherein the another solvent collection unit is heated by radiant heat from the turbo molecular pump. A closing member that freely opens and closes a space between the space in which the solvent collecting unit is disposed and the space in which the exhaust device is provided;
The reduced-pressure drying apparatus according to any one of claims 14 to 17, wherein the another solvent collection unit is provided downstream of the blocking member.   19. The vacuum drying apparatus according to claim 18, wherein the closing member is an automatic pressure control valve, and is provided in an exhaust pipe connecting the chamber and the exhaust apparatus. The chamber has a mounting table on the bottom plate for mounting the substrate,
The reduced-pressure drying apparatus according to claim 18, wherein the closing member includes a shutter that opens and closes between the mounting table and a side wall of the chamber. The chamber has a mounting table on the bottom plate for mounting the substrate,
The reduced-pressure drying apparatus according to claim 18, wherein the closing member includes a shutter that opens and closes between the mounting table and the top plate of the chamber.